This invention relates generally to molecular mass spectrometry and, in particular, to the use of aerogels and other coatings as collection media and matrix supports for MALDI-MS applications.
Matrix Assisted Laser Desorption and Ionization Mass Spectrometry (MALDI-MS) is a method that yields repeatable and consistent mass spectra for molecules which tend to fragment easily and uncontrollably under harsh mass spectroscopy ionization methods. Softer ionization methods such as MALDI have recently been used to ionize and desorb intact biomolecules as large as 300,000 Daltons into the gas phase for mass analysis.
The basis of MALDI is the interaction of a pulsed laser beam with a laser desorbing matrix material into which analyte molecules are dispersed. Pulsed laser energy is absorbed by the matrix and transferred to the analyte, causing it to be ionized and desorbed into the gas phase. In the process, the analyte chemically interacts with the fragment ions of the matrix, forming molecular adduct ions.
The MALDI process typically involves wet chemistry techniques, whereby a solution of the matrix molecule is physically mixed with a solution containing the analyte. The resulting mixture is applied to a sample probe, allowed to dry, and introduced to the mass spectrometer for analysis. The current use of wet chemistry is one of the drawbacks of the process, in that multiple steps are required, certain of which are not conducive to automation.
This invention provides novel techniques to modify and apply aerogel coatings, including the application of spray-coated aerogels. This approach improves upon the existing art by eliminating several of the wet chemical techniques previously needed for processes such as MALDI processing, as well as simplifying automation for processes such as continuous monitoring in a sensor based format. With respect to MALDI processing, the preferred embodiment uses an acid-doped silica aerogel coated tape as the collection media as well as the matrix support.
The ability to pattern and apply aerogels to surfaces which may have previously been difficult to apply opens up new areas in which aerogel technologies may prove useful. The demonstration of using aerogel as a matrix to hold a variety of analytes in a tape format is novel as well. Although aerogels are disclosed as a preferred matrix material, other materials may alternatively be used, including linoleic acids, oleic acids, PEG (polyelthylene glycol), preferably in tape format.